Fuction of Cathepsin B
Cathepsin B is an enzymatic protein belonging to the peptidase (or protease) families. In humans, it is coded by the CTSB gene.
The protein encoded by this gene is a lysosomal cysteine protease composed of a dimer of disulfide-linked heavy and light chains, both produced from a single protein precursor. It is a member of the peptidase C1 family. At least five transcript variants encoding the same protein have been found for this gene.
Cathepsin B was once suspected as a candidate protease participating in the conversion of β-amyloid precursor protein into the amyloid plaques found in Alzheimer's disease patients. However, this function is now known to be mediated by BACE1 protease. It is now thought that cathepsin B can degrade β-amyloid precursor protein into harmless fragments. Thus, it is conceivable cathepsin B may play a pivotal role in the natural defense against Alzheimer's disease.Overexpression ofcathepsin B has been associated with esophageal adenocarcinoma and other tumors.
Mutations in the CTSB gene have been linked to tropical pancreatitis, a form of chronic pancreatitis.